llvm/lib/Analysis/EHPersonalities.cpp

   1 //===- EHPersonalities.cpp - Compute EH-related information ---------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/Analysis/EHPersonalities.h"
  10 #include "llvm/ADT/StringSwitch.h"
  11 #include "llvm/IR/CFG.h"
  12 #include "llvm/IR/Constants.h"
  13 #include "llvm/IR/Function.h"
  14 #include "llvm/IR/Instructions.h"
  15 #include "llvm/Support/Debug.h"
  16 #include "llvm/Support/raw_ostream.h"
  17 using namespace llvm;
  18
  19 /// See if the given exception handling personality function is one that we
  20 /// understand.  If so, return a description of it; otherwise return Unknown.
  21 EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
  22   const GlobalValue *F =
  23       Pers ? dyn_cast<GlobalValue>(Pers->stripPointerCasts()) : nullptr;
  24   if (!F || !F->getValueType() || !F->getValueType()->isFunctionTy())
  25     return EHPersonality::Unknown;
  26   return StringSwitch<EHPersonality>(F->getName())
  27       .Case("__gnat_eh_personality", EHPersonality::GNU_Ada)
  28       .Case("__gxx_personality_v0", EHPersonality::GNU_CXX)
  29       .Case("__gxx_personality_seh0", EHPersonality::GNU_CXX)
  30       .Case("__gxx_personality_sj0", EHPersonality::GNU_CXX_SjLj)
  31       .Case("__gcc_personality_v0", EHPersonality::GNU_C)
  32       .Case("__gcc_personality_seh0", EHPersonality::GNU_C)
  33       .Case("__gcc_personality_sj0", EHPersonality::GNU_C_SjLj)
  34       .Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
  35       .Case("_except_handler3", EHPersonality::MSVC_X86SEH)
  36       .Case("_except_handler4", EHPersonality::MSVC_X86SEH)
  37       .Case("__C_specific_handler", EHPersonality::MSVC_TableSEH)
  38       .Case("__CxxFrameHandler3", EHPersonality::MSVC_CXX)
  39       .Case("ProcessCLRException", EHPersonality::CoreCLR)
  40       .Case("rust_eh_personality", EHPersonality::Rust)
  41       .Case("__gxx_wasm_personality_v0", EHPersonality::Wasm_CXX)
  42       .Case("__xlcxx_personality_v1", EHPersonality::XL_CXX)
  43       .Default(EHPersonality::Unknown);
  44 }
  45
  46 StringRef llvm::getEHPersonalityName(EHPersonality Pers) {
  47   switch (Pers) {
  48   case EHPersonality::GNU_Ada:       return "__gnat_eh_personality";
  49   case EHPersonality::GNU_CXX:       return "__gxx_personality_v0";
  50   case EHPersonality::GNU_CXX_SjLj:  return "__gxx_personality_sj0";
  51   case EHPersonality::GNU_C:         return "__gcc_personality_v0";
  52   case EHPersonality::GNU_C_SjLj:    return "__gcc_personality_sj0";
  53   case EHPersonality::GNU_ObjC:      return "__objc_personality_v0";
  54   case EHPersonality::MSVC_X86SEH:   return "_except_handler3";
  55   case EHPersonality::MSVC_TableSEH:
  56     return "__C_specific_handler";
  57   case EHPersonality::MSVC_CXX:      return "__CxxFrameHandler3";
  58   case EHPersonality::CoreCLR:       return "ProcessCLRException";
  59   case EHPersonality::Rust:          return "rust_eh_personality";
  60   case EHPersonality::Wasm_CXX:      return "__gxx_wasm_personality_v0";
  61   case EHPersonality::XL_CXX:
  62     return "__xlcxx_personality_v1";
  63   case EHPersonality::Unknown:       llvm_unreachable("Unknown EHPersonality!");
  64   }
  65
  66   llvm_unreachable("Invalid EHPersonality!");
  67 }
  68
  69 EHPersonality llvm::getDefaultEHPersonality(const Triple &T) {
  70   return EHPersonality::GNU_C;
  71 }
  72
  73 bool llvm::canSimplifyInvokeNoUnwind(const Function *F) {
  74   EHPersonality Personality = classifyEHPersonality(F->getPersonalityFn());
  75   // We can't simplify any invokes to nounwind functions if the personality
  76   // function wants to catch asynch exceptions.  The nounwind attribute only
  77   // implies that the function does not throw synchronous exceptions.
  78   return !isAsynchronousEHPersonality(Personality);
  79 }
  80
  81 DenseMap<BasicBlock *, ColorVector> llvm::colorEHFunclets(Function &F) {
  82   SmallVector<std::pair<BasicBlock *, BasicBlock *>, 16> Worklist;
  83   BasicBlock *EntryBlock = &F.getEntryBlock();
  84   DenseMap<BasicBlock *, ColorVector> BlockColors;
  85
  86   // Build up the color map, which maps each block to its set of 'colors'.
  87   // For any block B the "colors" of B are the set of funclets F (possibly
  88   // including a root "funclet" representing the main function) such that
  89   // F will need to directly contain B or a copy of B (where the term "directly
  90   // contain" is used to distinguish from being "transitively contained" in
  91   // a nested funclet).
  92   //
  93   // Note: Despite not being a funclet in the truest sense, a catchswitch is
  94   // considered to belong to its own funclet for the purposes of coloring.
  95
  96   DEBUG_WITH_TYPE("winehprepare-coloring", dbgs() << "\nColoring funclets for "
  97                                                   << F.getName() << "\n");
  98
  99   Worklist.push_back({EntryBlock, EntryBlock});
 100
 101   while (!Worklist.empty()) {
 102     BasicBlock *Visiting;
 103     BasicBlock *Color;
 104     std::tie(Visiting, Color) = Worklist.pop_back_val();
 105     DEBUG_WITH_TYPE("winehprepare-coloring",
 106                     dbgs() << "Visiting " << Visiting->getName() << ", "
 107                            << Color->getName() << "\n");
 108     Instruction *VisitingHead = Visiting->getFirstNonPHI();
 109     if (VisitingHead->isEHPad()) {
 110       // Mark this funclet head as a member of itself.
 111       Color = Visiting;
 112     }
 113     // Note that this is a member of the given color.
 114     ColorVector &Colors = BlockColors[Visiting];
 115     if (!is_contained(Colors, Color))
 116       Colors.push_back(Color);
 117     else
 118       continue;
 119
 120     DEBUG_WITH_TYPE("winehprepare-coloring",
 121                     dbgs() << "  Assigned color \'" << Color->getName()
 122                            << "\' to block \'" << Visiting->getName()
 123                            << "\'.\n");
 124
 125     BasicBlock *SuccColor = Color;
 126     Instruction *Terminator = Visiting->getTerminator();
 127     if (auto *CatchRet = dyn_cast<CatchReturnInst>(Terminator)) {
 128       Value *ParentPad = CatchRet->getCatchSwitchParentPad();
 129       if (isa<ConstantTokenNone>(ParentPad))
 130         SuccColor = EntryBlock;
 131       else
 132         SuccColor = cast<Instruction>(ParentPad)->getParent();
 133     }
 134
 135     for (BasicBlock *Succ : successors(Visiting))
 136       Worklist.push_back({Succ, SuccColor});
 137   }
 138   return BlockColors;
 139 }